U.S. patent application number 14/969532 was filed with the patent office on 2016-06-23 for image reconstructing apparatus, image reconstructing method, and non-transitory computer-readable storage medium.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Yoshihito Machida.
Application Number | 20160179346 14/969532 |
Document ID | / |
Family ID | 56129369 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160179346 |
Kind Code |
A1 |
Machida; Yoshihito |
June 23, 2016 |
IMAGE RECONSTRUCTING APPARATUS, IMAGE RECONSTRUCTING METHOD, AND
NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM
Abstract
An image reconstructing apparatus creates a reconstructed image
for every calculation operation by performing predetermined
repetitive calculation by iterative reconstruction for a plurality
of images obtained by acquiring an object from different angles,
extracts at least one reconstructed image under a predetermined
condition from the created reconstructed images, displays on a
display unit information corresponding to the extracted
reconstructed images and information corresponding to the extracted
reconstructed image, selects at least one reconstructed image in
accordance with an instruction of an operator on the display unit,
and outputs the selected reconstructed image.
Inventors: |
Machida; Yoshihito;
(Sagamihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
56129369 |
Appl. No.: |
14/969532 |
Filed: |
December 15, 2015 |
Current U.S.
Class: |
382/100 |
Current CPC
Class: |
G06T 2211/416 20130101;
A61B 8/5207 20130101; G06K 9/00798 20130101; G06T 7/55 20170101;
A61B 5/0073 20130101; G06T 7/0012 20130101; G06T 2207/20092
20130101; G06K 9/00818 20130101; G06T 2211/421 20130101; G06T
2207/10124 20130101; G06T 2207/30168 20130101 |
International
Class: |
G06F 3/0484 20060101
G06F003/0484; G06K 9/46 20060101 G06K009/46; G06T 7/00 20060101
G06T007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2014 |
JP |
2014-259276 |
Claims
1. An image reconstructing apparatus comprising: a creation unit
configured to create a reconstructed image for every calculation
operation by performing predetermined repetitive calculation by
iterative reconstruction for a plurality of images obtained by
acquiring an object from different angles; an extraction unit
configured to extract at least one reconstructed image under a
predetermined condition from the reconstructed images created by
the creation unit; a selection unit configured to display on a
display unit information corresponding to the reconstructed images
extracted by the extraction unit and information corresponding to
the extracted reconstructed image, and to select at least one
reconstructed image in accordance with an instruction of an
operator on the display unit; and an output unit configured to
output the at least one reconstructed image selected by the
selection unit.
2. The apparatus according to claim 1, wherein the extraction unit
extracts the at least one reconstructed image based on a
calculation count of the repetitive calculation, and the selection
unit displays, on the display unit, the calculation count
corresponding to the reconstructed image extracted by the
extraction unit.
3. The apparatus according to claim 1, wherein the extraction unit
extracts the at least one reconstructed image based on a feature of
each of the reconstructed images created by the creation unit, and
the selection unit displays, on the display unit, the feature
corresponding to the reconstructed image extracted by the
extraction unit.
4. The apparatus according to claim 3, wherein the feature is a
feature within a specific range of each of the reconstructed images
created by the creation unit.
5. The apparatus according to claim 3, wherein the feature includes
a standard deviation of pixel values of each of the reconstructed
images created by the creation unit.
6. The apparatus according to claim 3, wherein the feature includes
an average value of absolute values of differences between pixels
of an image before the repetitive calculation and pixels of a
forward projection image obtained at a creation stage of each of
the reconstructed images created by the creation unit.
7. The apparatus according to claim 1, wherein the extraction unit
extracts the at least one reconstructed image based on a
coefficient obtained by comparing the image before the repetitive
calculation and the forward projection image obtained at a creation
stage of each of the reconstructed images created by the creation
unit, and the selection unit displays, on the display unit, the
coefficient corresponding to the reconstructed image extracted by
the extraction unit.
8. The apparatus according to claim 1, wherein the selection unit
simultaneously displays, on the display unit, the plurality of
reconstructed images extracted by the extraction unit and pieces of
information corresponding to the extracted reconstructed
images.
9. The apparatus according to claim 1, wherein if there are a
plurality of objects, the selection unit simultaneously displays,
for each of the objects, on the display unit, the reconstructed
images extracted by the extraction unit and pieces of information
corresponding to the extracted reconstructed images.
10. The apparatus according to claim 9, wherein in synchronism with
information corresponding to one of the reconstructed images
extracted by the extraction unit, the selection unit displays, on
the display unit, another one of the reconstructed images extracted
by the extraction unit.
11. The apparatus according to claim 1, wherein if there are a
plurality of objects, a reconstructed image created for one of the
plurality of objects is used as a reference to create another
reconstructed image.
12. An image reconstructing method comprising: creating a
reconstructed image for every calculation operation by performing
predetermined repetitive calculation by iterative reconstruction
for a plurality of images obtained by acquiring an object from
different angles; extracting at least one reconstructed image under
a predetermined condition from the reconstructed images created in
the creating; selecting at least one reconstructed image in
accordance with an instruction of an operator on a display unit by
displaying, on the display unit, the reconstructed image extracted
in the extracting and information corresponding to the extracted
reconstructed image; and outputting the at least one reconstructed
image selected in the selecting.
13. A non-transitory computer-readable storage medium storing a
computer program for causing a computer to execute a method of an
image reconstructing apparatus, the method comprising: creating a
reconstructed image for every calculation operation by performing
predetermined repetitive calculation by iterative reconstruction
for a plurality of images obtained by acquiring an object from
different angles; extracting at least one reconstructed image under
a predetermined condition from the reconstructed images created in
the creating; selecting at least one reconstructed image in
accordance with an instruction of an operator on a display unit by
displaying, on the display unit, the reconstructed image extracted
in the extracting and information corresponding to the extracted
reconstructed image; and outputting the at least one reconstructed
image selected in the selecting.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image reconstructing
apparatus, an image constructing method, and a non-transitory
computer-readable storage medium and, more particularly, to a
technique of outputting the image quality of an image obtained by
iterative reconstruction.
[0003] 2. Description of the Related Art
[0004] An imaging apparatus acquires a plurality of images from
different angles, and creates a reconstructed image from these
images using a technique called an image reconstructing method. As
image reconstructing methods, methods called a filtered back
projection method and iterative reconstruction have been described
in the Handbook of Medical Imaging, Medical Imaging Technology, in
2012.
[0005] Among others, the iterative reconstruction is an image
reconstructing method of performing calculation by repeating
forward projection for calculating a projected image from a
reconstructed image obtained by back projection (to be described
later) and back projection for calculating a reconstructed image
from the projected image. This reconstructing method calculates a
coefficient by comparing the projected image obtained from the
reconstructed image with an image acquired by an imaging apparatus,
and performs back projection using the coefficient. Therefore, the
image quality of a reconstructed image changes every time
calculation is repeated. In this reconstructing method, it is
expected to obtain the effect of obtaining a less noisy image while
maintaining the sharpness. However, if repetitive calculation is
excessively performed, an attempt to reproduce noise in a acquired
image is made, thereby unwantedly increasing noise.
[0006] Japanese Patent Laid-Open No. 2006-25868 describes a method
in which when performing reconstruction by iterative
reconstruction, a region of interest is set on a reconstructed
image as an intermediate result, and it is determined based on the
standard deviation of the region whether to further perform
calculation.
[0007] There are various applications and purposes of reconstructed
images, which require different image qualities. It is, therefore,
necessary to construct a system that can satisfy the
requirements.
SUMMARY OF THE INVENTION
[0008] According to one aspect of the present invention, there is
provided an image reconstructing apparatus which comprises a
creation unit configured to create a reconstructed image for every
calculation operation by performing predetermined repetitive
calculation by iterative reconstruction for a plurality of images
obtained by acquiring an object from different angles; an
extraction unit configured to extract at least one reconstructed
image under a predetermined condition from the reconstructed images
created by the creation unit; a selection unit configured to
display on a display unit information corresponding to the
reconstructed images extracted by the extraction unit and
information corresponding to the extracted reconstructed image, and
to select at least one reconstructed image in accordance with an
instruction of an operator on the display unit; and an output unit
configured to output the at least one reconstructed image selected
by the selection unit.
[0009] Further features of the present invention will become
apparent from the following description of exemplary embodiments
(with reference to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a block diagram showing the arrangement of an
image reconstructing apparatus 100;
[0011] FIG. 2 is a flowchart illustrating a processing procedure
executed by the image reconstructing apparatus 100;
[0012] FIG. 3 is a schematic view showing an example of an image
selection unit 107;
[0013] FIG. 4 is a flowchart illustrating a processing procedure
executed by the image selection unit 107;
[0014] FIG. 5 is a schematic view showing an example of the image
selection unit 107;
[0015] FIG. 6 is a schematic view showing an example of an image
selection unit 600;
[0016] FIG. 7 is a block diagram showing the arrangement of an
image reconstructing apparatus 700; and
[0017] FIG. 8 is a flowchart illustrating a processing procedure
executed by the image reconstructing apparatus 700.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
[0018] An image reconstructing apparatus 100 according to the first
embodiment will be described with reference to FIGS. 1 to 4. FIG. 1
is a block diagram showing the arrangement of the image
reconstructing apparatus 100 according to this embodiment. As shown
in FIG. 1, the image reconstructing apparatus according to this
embodiment includes a projection image input unit 101, a forward
projection unit 102, a coefficient calculation unit 103, a back
projection unit 104, a reconstructed image extraction unit 105, a
calculation count determination unit 106, and an image selection
unit 107.
[0019] The operation of the above-described image reconstructing
apparatus 100 will be described with reference to FIG. 2. FIG. 2 is
a flowchart illustrating a processing procedure executed by the
image reconstructing apparatus 100. In step S201, the projection
image input unit 101 receives, as inputs, a plurality of images (to
be referred to as projection images hereinafter) acquired by an
imaging unit (not shown) from different angles, and outputs them to
the coefficient calculation unit 103. Steps S202 to S205 correspond
to a reconstructed image creation process by iterative
reconstruction. In step S202, the forward projection unit 102
receives, as an input, a reconstructed image output from the back
projection unit 104, and creates a forward projection image. Note
that if the calculation count is one, a reconstructed image
containing an appropriate value other than 0 is input to the
forward projection unit 102.
[0020] In step S203, the coefficient calculation unit 103 compares
the forward projection image with the projection image, thereby
performing coefficient calculation. In step S204, the back
projection unit 104 creates and updates the reconstructed image
based on the reconstructed image and a coefficient. In step S205,
the reconstructed image extraction unit 105 extracts one or more
reconstructed images from the created reconstructed images under a
predetermined condition, and outputs the extracted reconstructed
images to the image selection unit 107. At this time, the images
extracted and output from the reconstructed image extraction unit
105 are all saved in the image selection unit 107. Note that in
this embodiment, the reconstructed image extraction unit 105
extracts the created reconstructed image every time repetitive
calculation is performed.
[0021] In step S206, the calculation count determination unit 106
determines whether calculation has been performed a set number of
times. If the calculation has not been performed the set number of
times, the reconstructed image created by the back projection unit
104 is output to the forward projection unit 102, and the process
returns to step S202. If it is determined in step S206 that the
calculation has been performed the number of times, the process
advances to step S207. Note that the above-described the number of
times of calculation indicates the repetition count of steps S202
to S204. In step S207, the image selection unit 107 selects the
reconstructed image requested by an operator, and outputs the
selected reconstructed image. The operation of the image selection
unit 107 will be described in detail later. By performing the
processes in steps S201 to S207, the operator can acquire the
reconstructed image according to a purpose and application from the
reconstructed images.
[0022] The operation of the image selection unit 107 for selecting
and outputting, by the operator, the extracted reconstructed image
will be described with reference to FIGS. 3 and 4. The arrangement
of the image selection unit 107 will be described with reference to
FIG. 3. FIG. 3 is a schematic view showing an example of the image
selection unit 107 according to this embodiment. The image
selection unit 107 is constituted by display units for displaying
various kinds of information, and includes an image selection
instruction unit 301, an image display unit 302, a reconstruction
information display unit 303, and an image output instruction unit
304.
[0023] The image selection instruction unit 301 serves as a user
interface used by the operator to select and instruct one of the
reconstructed images output from the reconstructed image extraction
unit 105. The image selection instruction unit 301 according to
this embodiment is formed from two arrow buttons and a slide bar.
When the operator presses the up arrow button, the image selection
instruction unit 301 selects the reconstructed image with a smaller
calculation count among the reconstructed images. When the operator
presses the down arrow button, the image selection instruction unit
301 selects the reconstructed image with a larger calculation count
among the reconstructed images. In addition, when the operator
performs an operation of moving the slide bar upward, the image
selection instruction unit 301 selects the reconstructed image with
a smaller calculation count among the reconstructed images. When
the operator performs an operation of moving the slide bar
downward, the image selection instruction unit 301 selects the
reconstructed image with a larger calculation count among the
reconstructed images.
[0024] Note that the image selection instruction unit 301 according
to this embodiment need only be able to select and instruct one of
the plurality of reconstructed images. Any arrangement may be
adopted. For example, the arrow buttons and slide bar may be
arranged in the horizontal direction, or a calculation count may be
directly input. A button for switching the selected image for every
predetermined time when it is pressed may be added as the image
selection instruction unit 301. By adding such button, the operator
can sequentially select the plurality of reconstructed images by
performing one operation.
[0025] The image display unit 302 displays the reconstructed image
selected by the image selection instruction unit 301. The image
display unit 302 accepts an operation of changing the contrast and
luminance of the image, enlarged/reduced display, or the like, and
performs contrast and luminance adjustment, display magnification
adjustment, slice position adjustment, slice selection, or the like
in accordance with an operator instruction. Note that the number of
images displayed on the image display unit 302 is one in this
embodiment. However, the image display unit 302 may simultaneously
display a plurality of images corresponding to difference slice
sections or slice directions. This allows the operator to readily
select the reconstructed images.
[0026] The reconstruction information display unit 303 displays
additional information (reconstruction information) corresponding
to the reconstructed image selected by the image selection
instruction unit 301. The reconstruction information may contain a
calculation count corresponding to the selected reconstructed
image. In addition, the reconstruction information may contain, as
the feature values of the selected reconstructed image, the
standard deviation of the pixel values of the reconstructed image,
and the average value (to be referred to as a mean absolute error
hereinafter) of the absolute values of differences between the
pixels of the projection image (the image before calculation) and
those of the forward projection image obtained at a reconstructed
image creation stage. Note that the reconstruction information is
not limited to them.
[0027] The reconstruction information display unit 303 according to
this embodiment displays a graph showing the relationship between
the pieces of reconstruction information, for example, a graph
showing the relationship between the calculation count, the mean
absolute error, and the standard deviation. The reconstruction
information display unit 303 according to this embodiment adds an
arrow mark on the graph showing the relationship between the
calculation count, the mean absolute error, and the standard
deviation so as to readily determine the calculation count of the
image displayed on the image display unit 302. By displaying the
reconstruction information in addition to the reconstructed image,
the operator can select an output image using not only the
information of the reconstructed image but also information around
the reconstructed image.
[0028] The image output instruction unit 304 serves as a user
interface used by the operator to output and instruct the
reconstructed image selected by the image selection instruction
unit 301.
[0029] An example of processing performed using the above-described
image selection unit 107 will be described with reference to FIG.
4. FIG. 4 is a flowchart illustrating a processing procedure
executed by the image selection unit 107 according to this
embodiment. In step S401, the image display unit 302 and
reconstruction information display unit 303 display the image
extracted/output last from the reconstructed image extraction unit
105, and its reconstruction information, respectively. In step
S402, the operator selects the reconstructed image using the image
selection instruction unit 301. In step S403, the image display
unit 302 and reconstruction information display unit 303 display
the selected reconstructed image and its reconstruction
information, respectively. Furthermore, if the operator issues a
contrast, luminance, or magnification adjustment instruction or the
like, the image display unit 302 displays the image in accordance
with the instruction.
[0030] In step S404, the operator confirms the image and
information respectively displayed on the image display unit 302
and reconstruction information display unit 303. If the image and
information are desired ones, the process advances to step S405. If
the operator determines that the displayed image is not a desired
one, the process returns to step S402. In step S405, the operator
outputs the reconstructed image using the image output instruction
unit 304.
[0031] By performing the processes in steps S401 to S405, the
operator can select and output the desired image from the extracted
reconstructed images. Furthermore, in this embodiment, when the
reconstruction information of the reconstructed image is displayed
in addition to the image, quantitative image evaluation is
possible, and the operator readily selects the desired image.
[0032] [First Modification]
[0033] In this embodiment, the arrangement of extracting the
reconstructed image every time repetitive calculation is performed
is adopted. However, the reconstructed image may be extracted for
every predetermined number of times of repetitive calculation. For
example, an arrangement of extracting an image for every
predetermined number of times of repetitive calculation, for
example, for every 10 times of repetitive calculation, an
arrangement of extracting/outputting images at predetermined
timings, for example, extracting images at the 10th, 20th, 40th,
and 80th calculation operations, or the like may be adopted. This
can reduce the number of selection candidate reconstructed images,
and the operator can thus efficiently select the reconstructed
image.
[0034] [Second Modification]
[0035] In this embodiment, the arrangement of extracting the
reconstructed image every time repetitive calculation is performed
is adopted. However, the reconstructed image may be extracted for
each of other pieces of reconstruction information. For example, an
arrangement of extracting an image for each change amount in
predetermined coefficient, an arrangement of extracting an image
for each change amount in standard deviation of the pixel values of
a predetermined image, or the like may be adopted. This can narrow
down the selection candidates reconstructed images, and the
operator can thus efficiently select the reconstructed image.
[0036] [Third Modification]
[0037] In this embodiment, the number of reconstructed images to be
selected and output is one. However, a plurality of reconstructed
images may be output in accordance with a predetermined
application. With this operation, if a high-contrast image of
calcification or the like whose X-ray absorptance is relatively
high and a low-contrast image of a tumor or the like whose X-ray
absorptance is relative low are required, the operator can
efficiently select both the images.
[0038] [Fourth Modification]
[0039] In this embodiment, the arrangement of displaying, on the
image display unit 302, the image selected and instructed by the
image selection instruction unit 301 is adopted. However, the
present invention is not limited to this. FIG. 5 is a schematic
view showing an example of display of the image selection unit 107
according to the fourth modification. An arrangement may be adopted
in which a plurality of reconstructed images with different
calculation counts are displayed on the image display unit 302, and
directly selected, as shown in FIG. 5. This can facilitate an image
selection operation, and the operator can thus efficiently select
the reconstructed image.
[0040] [Fifth Modification]
[0041] In this embodiment, an arrangement of selecting the
reconstructed image after calculation is performed the preset
number of times is adopted. However, an operation of sequentially
displaying the images on the image selection unit 107, and
terminating repetitive calculation when an image output instruction
is issued may be performed. This can interrupt the processing when
the reconstructed image requested by the operator is output, and
the operator can thus efficiently acquire the reconstructed
image.
[0042] [Sixth Modification]
[0043] In this embodiment, an arrangement of displaying the feature
values of the pixel values of the reconstructed image is adopted.
However, the feature values of pixels values in a region of
interest (a specific range) may be displayed in the reconstructed
image. For example, the operator may designate a region of interest
in the reconstructed image, and calculate and display a standard
deviation in the region of interest. If the reconstructed images
are sequentially displayed as in the fifth modification, a unit of
designating a region of interest may be provided in the image
display unit 302, thereby allowing the operator to designate a
region of interest. This makes it easy to create an image having
image quality requested by the operator.
Second Embodiment
[0044] In the second embodiment, a method of performing
reconstructing processing and selection processing for two kinds of
reconstructed images of an object will be described. A method of
obtaining reconstructed images by individually acquiring and
reconstructing left and right breasts will be explained. The
arrangement and basic operation of an image reconstructing
apparatus are the same as in the first embodiment and a description
thereof will be omitted. A reconstructed image display method and
an image selection method which are different from those in the
first embodiment will be described.
[0045] FIG. 6 is a schematic view showing an example of display of
an image selection unit 600 according to this embodiment. Assume
that reconstructed images obtained by individually, sequentially
reconstructing left and right breasts in the same method as in the
first embodiment have been input to the image selection unit
600.
[0046] The image selection unit 600 includes image selection
instruction units 601, image display units 602, reconstruction
information display units 603, an image output instruction unit
604, and a synchronization instruction unit 605. Each image
selection instruction unit 601 serves as an interface used by the
operator to select and instruct a reconstructed image. There are
provided two image selection instruction units 601 including a
combination of two arrow buttons and a slide bar according to this
embodiment. The roles and arrangement of the respective arrow
buttons and slide bar are the same as in the first embodiment and a
description thereof will be omitted. This allows the operator to
select reconstructed images with different calculation counts as
left and right reconstructed images.
[0047] The synchronization instruction unit 605 serves as an
interface used by the operator to instruct whether to perform
selection and display processes of the left and right reconstructed
images in synchronism with each other. The synchronization
instruction unit 605 according to this embodiment includes a
checkbox. If the checkbox is checked, left and right reconstructed
images are selected in synchronism with each other. When one of the
two image selection instruction units 601 is operated, images with
the same calculation count are simultaneously selected as two kinds
of reconstructed images. By selecting left and right images in
synchronism with each other, the operator can readily obtain, by
one operation, images having undergone the same number of
calculation operations.
[0048] Note that as described in the first embodiment and the
second modification, if the reconstructed images to be selected are
obtained by the method of extracting an image for each change
amount in predetermined coefficient, the method of extracting an
image for each change amount in standard deviation of the pixel
values of a predetermined image, or the like, the images having the
same ordinal number of extraction are simultaneously selected. An
arrangement of selecting and displaying, in synchronism with each
other, images whose feature values such as standard deviations are
almost equal to each other may be adopted. This makes it possible
to simultaneously select images whose objective indices are equal
to each other, thereby further facilitating image selection.
[0049] The image display units 602 display the reconstructed images
selected by the image selection instruction units 601,
respectively. In this example, the image display units 602 display
the left and right images, respectively. That is, the image display
units 602 simultaneously display the reconstructed images for each
object. If the checkbox of the synchronization instruction unit 605
has been checked, an operation for changing the contrast and
luminance of each display image, enlarged/reduced display, or the
like is accepted, and the image display units 602 perform contrast
and luminance adjustment, display magnification adjustment, slice
position adjustment, slice selection, or the like in accordance
with an operator instruction in synchronism with each other. The
reconstruction information display units 603 display the pieces of
information of the reconstructed images selected by the image
selection instruction units 601, and display the pieces of
information of both the left and right images. The image output
instruction unit 604 serves as a user interface used by the
operator to instruct to output the reconstructed images selected by
the image selection instruction units 601.
[0050] Using the image selection unit 600 allows the operator to
readily select a plurality of kinds of images associated with each
other. Note that the method of selecting and outputting the
reconstructed images of the left and right breasts has been
explained in this embodiment. However, the present invention is not
limited to this, and this embodiment is applicable when different
reconstructed images are simultaneously displayed and selected. For
example, the embodiment is usable as a method of selecting images
of the same object or portion output under different image
processing conditions. The image processing conditions indicate the
pixel size of the reconstructed image, the slice thickness, the
pixel size of a projection image, and the like. For example, the
embodiment may be used as a method of selecting two kinds of
reconstructed images output under the image processing conditions
for outputting a high-resolution image having a small pixel size of
the reconstructed image and a small slice thickness and the image
processing conditions for outputting a low-noise image having a
large pixel size and a large slice thickness. This makes it easy to
select a plurality of kinds of images for different
applications.
Third Embodiment
[0051] In the third embodiment, a method of performing
reconstructing processing and selection processing for two kinds of
reconstructed images will be described. In this embodiment, the
arrangement and basic operation of an image reconstructing
apparatus are the same as in the first embodiment and a description
thereof will be omitted. A reconstructed image selection/output
method different from that in the first embodiment will be
described. To obtain reconstructed images by individually acquiring
and reconstructing left and right breasts, reconstructing
processing is performed for the left breast, a reconstructed image
to be output is selected, and then reconstructing processing of the
right breast is performed in accordance with the reconstruction
information of the selected image.
[0052] The arrangement of an image reconstructing apparatus 700
will be described with reference to FIG. 7. FIG. 7 is a block
diagram showing the arrangement of the image reconstructing
apparatus 700 according to this embodiment. As shown in FIG. 7, the
image reconstructing apparatus includes a projection image input
unit 701, a forward projection unit 702, a coefficient calculation
unit 703, a back projection unit 704, a reconstructed image
extraction unit 705, a calculation count determination unit 706,
and a reference image selection unit 707.
[0053] The operation of the above-described image reconstructing
apparatus 700 will be described with reference to FIG. 8. FIG. 8 is
a flowchart illustrating a processing procedure executed by the
image reconstructing apparatus 700 according to this embodiment. In
steps S801 to S807, reconstructing processing is performed using
acquired images of the left breast and a reconstructed image as a
reference is selected. Operations in steps S801 to S806 are the
same as in the first embodiment and a description thereof will be
omitted. In step S807, the operator uses the reference image
selection unit 707 to select a reconstructed image requested by the
operator, and the reference image selection unit 707 outputs the
selected reconstructed image. In step S808, the calculation count
of the reconstructed image as a reference is input to the
calculation count determination unit 706. In step S809, the
projection image input unit 701 receives projection images obtained
by acquiring the right breast from different angles by an imaging
apparatus (not shown), and outputs them to the coefficient
calculation unit 703.
[0054] In step S810, the forward projection unit 702 receives a
reconstructed image, and creates a forward projection image. Note
that if the calculation count is one, a reconstructed image
containing an appropriate value other than 0 is input to the
forward projection unit 702. In step S811, the coefficient
calculation unit 703 compares the forward projection image with the
projection image, thereby performing coefficient calculation. In
step S812, the back projection unit 704 creates and updates the
reconstructed image based on the reconstructed image and a
coefficient.
[0055] In step S813, the calculation count determination unit 706
determines whether calculation has been performed the number of
times input in step S808. If the calculation has not been performed
the number of times, the reconstructed image created by the back
projection unit 704 is output to the forward projection unit 702,
and the process returns to step S810. If it is determined in step
S813 that calculation has been performed the number of times, the
reconstructed image of the right breast is output, thereby
terminating the processing.
[0056] By performing the processes in steps S801 to S813 as
described above, the operator can efficiently acquire another
reconstructed image by using the first selected reconstructed image
as a reference.
[0057] Note that this embodiment has exemplified an example in
which the calculation counts of the reconstructed images of the
left and right breasts are equalized. The present invention,
however, is not limited to this. For example, a method of
equalizing the feature values of images such as the standard
deviations of images or the like may be used. This makes it easy to
obtain an image with image quality equal to that of a reference
image.
[0058] Note that this embodiment has described the method of
selecting and outputting the reconstructed images of the left and
right breasts. However, the present invention is not limited to
this, and is applicable when a plurality of reconstructed images
are output. For example, this embodiment is also usable, for
example, when a reconstructed image of one subject is used as a
reference to output reconstructed images of the subject, which are
subsequently reconstructed, and when a reconstructed image obtained
by acquiring and reconstructing a simulated phantom which is not
human body data is used as a reference to output a reconstructed
image of an actual subject.
Other Embodiments
[0059] Embodiment(s) of the present invention can also be realized
by a computer of a system or apparatus that reads out and executes
computer executable instructions (e.g., one or more programs)
recorded on a storage medium (which may also be referred to more
fully as a `non-transitory computer-readable storage medium`) to
perform the functions of one or more of the above-described
embodiment(s) and/or that includes one or more circuits (e.g.,
application specific integrated circuit (ASIC)) for performing the
functions of one or more of the above-described embodiment(s), and
by a method performed by the computer of the system or apparatus
by, for example, reading out and executing the computer executable
instructions from the storage medium to perform the functions of
one or more of the above-described embodiment(s) and/or controlling
the one or more circuits to perform the functions of one or more of
the above-described embodiment(s). The computer may comprise one or
more processors (e.g., central processing unit (CPU), micro
processing unit (MPU)) and may include a network of separate
computers or separate processors to read out and execute the
computer executable instructions. The computer executable
instructions may be provided to the computer, for example, from a
network or the storage medium. The storage medium may include, for
example, one or more of a hard disk, a random-access memory (RAM),
a read only memory (ROM), a storage of distributed computing
systems, an optical disk (such as a compact disc (CD), digital
versatile disc (DVD), or Blu-ray Disc (BD).TM.), a flash memory
device, a memory card, and the like.
[0060] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0061] This application claims the benefit of Japanese Patent
Application No. 2014-259276, filed Dec. 22, 2014, which is hereby
incorporated by reference herein in its entirety.
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